The goal of this Program will be to develop an HIV-1 vaccine that is targeted to mucosal surfaces. There are 4 central scientific aims. First, to determine whether delivery of DNA or Sindbis replicon candidate vaccines (vSIN) by mucosal routes is safe and immunogenic. Second, to determine the most appropriate mucosal or systemic routes needed to generate T and B cell responses in the vagina and rectum. Third, to study the inductive phase of vaccination across mucosal surfaces, with special emphasis on antigen presentation and T cell trafficking. And lastly, to improve the methods and assays used to measure mucosally derived or mucosally directed T cell responses. The investigations will focus on the systematic evaluation of optimized PLG-DNA and vSIN vaccines, both of which can be used to produce millions of clinical doses. The constructs will first be studied in the murine model to determine gene expression and relative immunogenicity. The murine system will also be used to evaluate the infection of dendritic and presenting cells at mucosal surfaces, and the trafficking of effector B and T cells after mucosal immunization. Macaque challenge studies will be used to determine the optimum route and sequencing of mucosal vaccination for induction of immune responses in the vagina and rectum. A macaque study also will be designed to determine the relative immunogenicity of HIV vaccine constructs in the macaque, as compared to immunogenicity in humans. The 4 clinical studies in Project 3 and 4 are designed to assess safety and immunogenicity of mucosal vaccination, and to allow for development of techniques that will assess human T cell immunity at mucosal surfaces. The routes, constructs to be used, and design of these clinical trials will be dependent on the results of the studies conducted by Projects 1 and 2. Two essential cores will support all of these Projects. The Vaccine Technology Core will be located at the Chiron Corporation, which will supply the necessary constructs, vaccine technology expertise, reagents, and manufacturing capability. An Administrative Core will be responsible for the coordination, communication, and financial management of the Program.